This invention relates to a process for the hydroconversion of heavy hydrocarbon oils, and more specifically to a process for hydrocracking heavy hydrocarbon oils in the presence of a catalyst.
A variety of processes have been hitherto proposed for catalytically converting, by reaction with hydrogen, heavy hydrocarbon oils containing significant amounts of extremely high molecular weight compounds, such as vacuum residues, into more valuable, light hydrocarbon oils. Such treatment generally employs one or more metals such as molybdenum, nickel and cobalt supported on a carrier such as alumina or silica as the catalyst. The reaction is generally carried out at a relatively high temperature so as to effect such hydrotreatment with practically acceptabe efficiency. At such a high reaction temperature, however, polycondensation of the high molecular weight compounds such as asphaltenes is accelerated, thereby forming a large amount of coke. The coke thus formed can deposit on the catalyst particles, causing the deterioration of the catalyst, clogging of the reactor and the like troubles. While an increase in the amount of hydrogen feed is effective to suppress the coke formation, such as increase in hydrogen consumption is not acceptable from the economic point of view.